/Engine/Source/Runtime/UMG/Public/Blueprint/SlateBlueprintLibrary.h
Translates a screen position in pixels into the local space of a widget with the given geometry. If bIncludeWindowPosition is true, then this method will also remove the game window's position (useful when in windowed mode).
static void ScreenToWidgetLocal ( [UObject](API\Runtime\CoreUObject\UObject\UObject) * WorldContextObject, const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & Geometry, FVector2D ScreenPosition, FVector2D & LocalCoordinate, bool bIncludeWindowPosition )